Biodegradable Transparent Substrate Based on Edible Starch

Subscriber access provided by UCL Library Services

Energy, Environmental, and Catalysis Applications

Biodegradable Transparent Substrate Based on Edible StarchChitosan Embedded with Nature-Inspired Three-Dimensionally Interconnected Conductive Nanocomposites for Wearable Green Electronics Jinlei Miao, Haihui Liu, Yongbing Li, and Xingxiang Zhang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b04291 • Publication Date (Web): 15 Jun 2018 Downloaded from http://pubs.acs.org on June 15, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Biodegradable Transparent Substrate Based on Edible Starch-Chitosan Embedded

with

Nature-Inspired

Three-Dimensionally

Interconnected

Conductive Nanocomposites for Wearable Green Electronics Jinlei Miao, Haihui Liu, Yongbing Li, Xingxiang Zhang* State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Municipal Key Laboratory of Advanced Fiber and Energy Storage, School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China ABSTRACT: Electronic waste (E-waste) contain large environmental contaminants such as toxic heavy metals and hazardous chemicals. These contaminants would migrate into drinking water or food chains and pose a serious threat to environment and human health. Biodegradable green electronics has great potential to address the issue of E-waste. Here we report on a novel biodegradable and flexible transparent electrode, integrate three-dimensionally (3D) interconnected conductive nanocomposites into edible starch-chitosan based substrates. Starch and chitosan are extracted from abundant and inexpensive potato and crab shells respectively. Nacre-inspired interface design are introduced to construct 3D interconnected single wall carbon nanotubes (SCNT)-pristine graphene (PG)-conductive polymer network architecture. The inorganic 1D SCNT and 2D PG sheets are tightly cross-linked

together

at

poly(3,4-ethylenedioxythiophene)

the

junction

(PEDOT)

interface

chains.

The

by

long

formation

organic of

a

3D

conductive continuous

SCNT-PG-PEDOT conductive network not only leading to a low sheet resistance but also a superior flexibility. The flexible transparent electrode possesses an excellent optoelectronic performance: typically, a sheet resistance of 46 Ω/sq with transmittance of 83.5 % at a typical wavelength of 550 nm. The sheet resistance of electrode slightly increased less than 3 % even after hundreds of bending cycles. The lightweight flexible and biocompatible transparent electrode could conform to skin topography or any other arbitrary surface naturally. The edible starch-chitosan substrate based transparent ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 28

electrodes could be biodegraded in lysozyme solution rapidly at room temperature without producing any toxic residues. SCNT-PG-PEDOT can be recycled via a membrane process for further fabrication of conductive and reinforcement composites. This high performance biodegradable transparent electrode is a promising material for next-generation wearable green optoelectronics, transient electronics and edible electronics. KEYWORDS: electronic waste, starch, chitosan, flexible, transparent electrode, three-dimensionally interconnected, edible electronics 1. Introduction With the update rate of electronics such as smart cell phones and tablets turns faster, the lifetime of electronics is becoming increasingly shorter. Large volume of electronic waste (E-waste) are routinely discarded due to the high recycling cost.1,2 Discarded E-waste would release large toxic heavy metals and hazardous chemicals, which would enter the biological systems via soil, receiving waters and food chains.3 E-waste have been considered to be the fastest growing component of solid waste and posed serious environmental and ecological problems.4 Furthermore, some electronic products generated serious environmental and ecological impacts throughout the life cycle, even starting from the acquisition of raw materials.1 Biodegradable electronics can degrade or dissolve into surrounding environment naturally, and then disappeared with no threats to health and ecosystems.5, 6 Therefore, it is highly desirable to develop biodegradable electronics derived from nature to address the current thorny E-waste issue.7-10 Attempts have been made to develop natural substrates to replace traditional semiconductors and other inorganic substrates, such as Bombyx mori silk fibroin and wood-derived cellulose.11-14 However, silk fibroin solution is very easily denatured and cannot be preserved for a long time, which hinders its applications in large scale fabrication of electronics.15 Cellulose paper based substrates suffer the drawbacks of high surface roughness, which would cause the short circuit of the electronics. Planarization layers are always introduced to reduce the surface feature size to the sub-nanometer scale. However, the introduction of planarization process diminishes the low-cost ACS Paragon Plus Environment

Page 3 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


advantage of material and limits the applicability to large-area fabrication methods.16 Develop high performance natural substrates with low cost and simple process remains as an ambitious objective. On the other hand, flexible and wearable electronics have recently attracted growing attention for their potential applications in flexible and stretchable displays,17 personalized health monitoring,18 wireless communication,19 human–machine interfaces20 and so forth.21, 22 Transparent electrodes (TE) are essential elements in a wide range of optoelectronic and “invisible” electronic circuits devices.23 Currently, indium tin oxide (ITO) is the most widely used conductive material in conventional TE. However, ITO is not suitable for flexible and wearable electronics due to its brittleness and toxic nature.24-25 Recent studies have demonstrated that the hybrid nanomaterial of one dimensional (1D) single wall carbon nanotube (SCNT) and 2D pristine graphene (PG) is quite promising to replace ITO due to their excellent thermal, chemical stability, and outstanding mechanical flexibility.26-28 Unfortunately, although SCNT and PG exhibit high intrinsic electrical conductivity and flexibility, a random mixture of SCNT and PG suffers high nanotube-sheet interfacial junction resistance. The weak junction interfacial interaction not only hinders the charge carrier transfer but also induces mechanical instability of the conductive network.26, 29 Recently, in-situ growth covalently bonded SCNT-PG has been demonstrated to be an effective method to construct 3D interconnected SCNT-PG conductive network.30 However, the chemical vapor deposition process always requires thousands degree and leads to serious energy consumption issue. Construct tightly interconnected SCNT-PG conductive network for high performance flexible TE via sustainable strategies is still a huge challenge. To address the above challenges, embedding junction-interconnected SCNT-PG conductive networks into biomass-derived substrates would be a good choice. Potato starch is an attractive raw material for natural substrate due to its cheap, abundant, biodegradable, edible and water-soluble.31 Unfortunately, wide applications of flexible plasticized starch films are limited by its poor mechanical property.32 Recently, much attention has been focused on polymer blends to overcome the disadvantages of biopolymers to be used in biodegradable and implantable electronics.33,34 Jeong and coworkers added ACS Paragon Plus Environment


Page 4 of 28

polyvinyl alcohol (PVA) to starch to enhance the mechanical property of natural starch film and took it as a substrate for flexible organic transistors.16 However, PVA is a synthetic polymer with a low biodegradability and high cost compared to starch. Chitosan is a natural carbohydrate derived from chitin and available from waste product of crustacean shells.35 A blend of starch and chitosan (SC) would bring opportunities to develop new natural substrate for flexible and wearable electronics due to their molecular miscibility.36 Nacre-inspired interface design are expected to play a key role in assemble individual SCNT and PG into macro-size interconnected conductive networks. Natural nacre owns remarkably mechanical properties such as twice as strong and 1000-folds tougher than its constituents. This phenomena is attributed to: (1) a “ brick and mortar” layered architecture alternatively packed with 2D aragonite calcium carbonate platelets, 1D nanofibrillar chitin and protein. (2) multi-interfacial interactions between inorganic platelets and organic protein.37 Hence, a stretchable and conductive organic macromolecule is highly desired to enhance interfacial interaction between inorganic

1D

SCNT

and

2D

PG

sheets.

Intrinsically

conductive

and

stretchable

poly(3,4-ethylenedioxythiophene) (PEDOT) macromolecule is quite promising to be the candidate as it owns the highest reported conductivity among the solution processed polymers. Furthermore, transition between folding and stretching of macromolecular chains providing large amounts of free volume for polymer chain movements instead of the destructive interfacial sliding between SCNT and PG.38 In this work, we report a simple yet efficient green method for creating highly biodegradable and flexible TE by embedding nacre-inspired 3D SCNT-PG-PEDOT interpenetrating conductive network into transparent edible SC substrates. The procedure for preparing TE is demonstrated in Figure 1. The edible starch and chitosan are extracted from natural potato and crab shells, which are inexpensive, abundant, and biodegradable. The TE exhibit excellent optoelectronic performance and mechanical stability with a low sheet resistance of 46 Ω/sq and a transmittance of 83.5 % at a typical wavelength of 550 nm, nearly unchanged after hundreds of bending cycles. Moreover, the edible substrate of TE could

ACS Paragon Plus Environment

Page 5 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


be biodegraded by lysozyme, which is very widely distributed in nature, such as animal tissues and tissue fluids. SCNT-PG-PEDOT can be recycled via a membrane process for further fabrication of conductive and reinforcement composites. This strategy opens a new path to solve the current E-waste issue and develop next-generation wearable green electronics and edible electronics.

Figure 1. Schematic illustration of the fabrication process for biodegradable and flexible 3D interconnected SCNT-PG-PEDOT based TE.

2. Experimental section Materials Potato starch was purchased from a local Tianjin Walmart market, Poly(styrenesulfonate) (PSS), lysozyme and chitosan derived from crab shells were purchased from Sinopharm Group Chemical Reagent Co. Ltd., Shanghai, China. Glycerin, acetic acid (CH3COOH), sodium acetate (CH3COONa) and dimethyl sulphoxide (DMSO) were purchased from Tianjin Guangfu Fine Chemical Research Institute. Mechanically exfoliated PG powder (diameter of 2 to 10 µm, thickness less than 5 nm) was purchased from Xiamen Knano Graphene Technology Co. Ltd., Xiamen, China. SCNT (diameter of



Page 6 of 28

0.8--1.6 nm, length of 5-30 µm) grown by chemical vapor deposition was provided by Chengdu Organic Chemicals Co. Ltd., Chengdu, China. PEDOT:PSS solution (Clevios PH 1000) with concentration of 1.3% by weight and PSS to PEDOT weight ratio of 2.5 was purchased from H.C. Starck. All reagents were used as received. Fabrication of SC transparent solution Potato solution (1%, w/v) was prepared by dissolving potato starch powder in water and stirred at 90 ºC for 20 min. Chitosan powder was dissolved in CH3COOH solution (1%, v/v) and stirred overnight to prepare chitosan solution (1%, w/v). A series of SC transparent solutions were prepared via blend starch solution and chitosan solution by different volume ratios (5:1, 4:2, 3:3, 2:4, 1:5). Pure starch solution and chitosan solution without blending were also prepared, respectively. Plasticizer glycerol was added at 25% (w/w) of the total solid weight in solution. The transparent solution was subjected to vacuum defoaming to remove bubbles before casting. Fabrication of 3D interconnected SCNT-PG-PEDOT conductive conductors To make a flexible SCNT-PG-PEDOT conductive conductor, a homogeneously SCNT-PG-PEDOT ink was first prepared. Typically, 5 wt% DMSO was added to PEDOT:PSS solution and then filtered through a 0.45 µm polyvinyl difluoride (PVDF) syringe filter. Then, a 1:1 weight ratio of SCNT/PG was dispersed in PEDOT:PSS solution (5 mg/mL) and vigorously stirred for 60 min, and then ultrasonicated through tip sonication for 30 min to obtain a well-dispersed ink. As a comparison, SCNT/PG mixture dispersed in merely PSS solution was also fabricated. At last, the SCNT-PG-PEDOT ink was diluted with ultrapure water at a volume ratio of 2:3 and air-sprayed onto heat-resistant petri dish by airbrush (Fuso Seiki Co. Ltd., Japan). The samples were dried in a vacuum oven at 100 ºC for 1 h to obtain 3D interconnected SCNT-PG-PEDOT conductor. A series of SCNT-PG-PEDOT conductors with different thickness were fabricated by varying the spray coating time. In this study, the spray coating pressure was fixed at 3 bar supported by nitrogen gas and the distance between the substrate and the nozzle was10 cm. ACS Paragon Plus Environment

Page 7 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Fabrication of edible SC substrate based TE Transparent SC solutions were casted onto the SCNT-PG-PEDOT coated petri dishes and kept in an oven at 60°C until the solution was evaporated. Finally, biodegradable TE with 3D interconnected SCNT-PG-PEDOT architecture conductive networks were obtained by peeling off the SC substrate from the petri dish. Characterization The surface morphology of samples was characterized by field-emission scanning electron microscopy (FE-SEM, Hitachi S-4800). Surface roughness of the samples was evaluated using an atomic force microscope (AFM, Agilent 5500, US). Transmission electron microscopy (TEM) was performed using a Hitachi H-800 electron microscope. Fourier transform infrared (FT-IR) spectra of the samples was obtained by a spectrometer (Bruker TERSOR37, German). X-ray photoelectron spectroscopy (XPS) measurements were conducted on a K-Aepna XPS system (Thermo Fisher, USA). A Raman spectroscope (Raman, Horiba Jobin Yvon Xplora) was used to characterize the nanostructures of samples. X-ray powder diffraction (XRD) patterns was obtained using a Rigaku D/MAX-gA diffractometer with filtered Cu Kα radiation (λ=0.15406 nm). The sheet resistance was measured by four-point probe method (Keithley 2700 multi-meter). The optical transmittance was measured using a UV–vis spectrophotometer (TU-1901). The mechanical property of the biodegradable substrates was analyzed by a mechanical tester (SANS -20 kN, China) with a crosshead speed of 5 mm/min at room temperature. 3. Results and Discussion To fabricate biodegradable and flexible TE, we first make a starch and chitosan solution. Natural potato and crab shells derived solution exhibit excellent optical properties as shown in Figure 1. It should be noted that potato starch and chitosan were dissolved in water and acetic acid by a green process without harsh chemistry procedures or solvent recovery problems. They are not only abundant and inexpensive but also biodegradable, biocompatible and even edible.39 In order to improve the ACS Paragon Plus Environment


Page 8 of 28

performance of the pure starch films, different amounts of chitosan were added to the starch. As shown in Figure 2a, the tensile strength and elongation values of SC films first increased with the addition of chitosan. The maximum of tensile strength and elongation are 30.2 MPa and 35.6% respectively at a SC ratio of 3:3, which are both higher than pure starch and chitosan films. However, the transmittance of SC (3:3) film is lower than 90% at a typical wavelength of 550 nm as shown in Figure 2b, which would affect the optoelectronic properties of TE. The transparency of SC (2:4) film is above 90% at 550 nm with a relative high tensile strength (27.4 MPa) and elongation (31.3%) values. The plasticized SC (2:4) film exhibits outstanding transparency and flexibility (inset of Figure 2b). Hence, we choose SC (2:4) film as the candidate for biodegradable and flexible transparent substrate. The diameter and thickness of the edible and flexible SC substrate is 5 cm and ~ 40 µm respectively. FTIR spectroscopy was performed to examine the intermolecular interactions between chitosan and starch (Figure 2c). In the spectrum for potato starch film, the broad band occurs at 3400 cm-1 was due to OH stretching. The sharp band at 2928 cm-1 corresponded to the C-H stretching associated with the ring methane hydrogen atoms. The bands at 1654 cm-1 and 1465 cm-1 were attributed to the δ(O-H) bending of water and CH2. The bands from 765 to 1157 cm-1 corresponded to the C-O bond stretching.36 In the spectrum for chitosan film, the broad band at 3400 cm-1 was due to OH stretching and NH stretching. The band at 1552 cm-1 was due to the NH bending (amide II). A small peak near 1656 cm-1 was attributed to the C=O stretching (amide I), while the one at 1738 cm-1 corresponded to carbonyl group in the film.40 For SC film (without glycerol), the amino peak of chitosan shifted from 1552 to 1557 cm-1, indicating the formation of intermolecular hydrogen bonds between NH3+ of chitosan and -OH groups of starch. The significant enhancement of mechanical property of edible SC blends compared with natural starch and chitosan was attributed to the formation of intermolecular hydrogen bonds between NH3+ of chitosan and -OH groups of starch. The number of starch intramolecular hydrogen bonds decreased and intermolecular hydrogen bonds increased by adding a small amount of chitosan into starch. ACS Paragon Plus Environment

Page 9 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The XRD patterns further confirmed the intermolecular interactions present between starch and chitosan as shown in Figure 2d (without glycerol). A broad amorphous peak was observed in the SC film, demonstrating the intermolecular interactions between the NH3+ in chitosan and -OH groups in starch limited the molecular movement and suppressed the crystallization.40 Figure 2e depicts the intermolecular interactions mechanism between starch chains and chitosan chains in SC film. The addition of chitosan induced the formation of intermolecular hydrogen bonds between -OH groups of starch and NH3+ of chitosan and the decreasing of intramolecular hydrogen bonds in starch chains. Then the 3D cross-linked structure was formed between starch chains and chitosan chains in edible SC film and enhanced the mechanical property of the film. Furthermore, the SC film is very lightweight. The SC film without adding plasticizer glycerol could stand on a flower like dog’s tail (Setaira viridis (L.) Beauv). Interestingly, the slender grass of the flower like dog’s tail was not bent at all (Figure 2f). The lightweight is an essential requirement for on-skin devices as it should induce minimal discomfort associated with wear.41

Figure 2. (a) Effect of SC ratio on the tensile strength and elongation of biodegradable substrate. (b) Transmittance spectra of SC films. Inset is the photographic image of the flexible and transparent SC substrate. (c) FTIR spectra of ACS Paragon Plus Environment


Page 10 of 28

chitosan film, starch film, and SC film (2:4). (d) XRD patterns of starch powder, starch film, chitosan powder, chitosan film, SC film (2:4). (e) Schematic representation of the probable mechanism for the formation of the cross-linked SC structure. (f) The SC substrate standing on a flower like dog’s tail (Setaira viridis (L.) Beauv).

Apart from the mechanical and optical properties, surface morphology of the substrates also affects many properties important for optoelectronic device applications. The surface roughness needs to be minimized to avoid short circuits in the optoelectronic devices.42 We investigated the surface morphology of SC substrates (2:4) with AFM. As shown in Figure 3a and b, the surface topography is relatively smooth and continuous. The surface roughness average (Ra) is ~ 7 nm and such a low surface roughness is comparable to other biodegradable substrates such as nano-fibrillated cellulose and silk fibroin.15, 43

Figure 3. (a) AFM topographic images of SC film (2:4) and (b) its 3D image.

SCNT and PG hybrids is used as flexible transparent conductor embedded in edible host SC matrices to form a percolating conductive network. Here, PG represents that the graphene sheets were mechanically exfoliated from graphite directly without went-through any chemical treatments, since the chemical treatments such as oxidation would induce structural defects and thus destroy the electronic structure of graphene.44 In order to form a continuous 3D interconnected SCNT-PG conductive network, nacre-inspired interface design are introduced. Nacre exhibits outstanding macro-sized properties by


Page 11 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


assemble micro-scale inorganic mineral platelets and organic glue into a“brick and mortar” like layered architecture as shown in Figure 4a. This provides a novel strategy to solve the challenge that assemble microscale graphene and SCNT into high performance macro-size conductive network by a green process. We prepared a homogenous precursor conductive ink by dispersed PG and SCNT in PEDOT:PSS solution. As shown in Figure 4b-d, when SCNT/PG mixture dispersed in merely PSS solution, SCNT and PG are loosely connected. SCNT and PG are stacked randomly and easily slipped away from each other due to the weak interfacial interaction between them.29,30 In contrast, when SCNT/PG mixture dispersed in PEDOT:PSS, the 1D SCNT and 2D PG are distributed uniformly and stacked tightly on the surface of each other as shown in Figure 4e-g. More interestingly, in the 3D interconnected SCNT-PG-PEDOT conductive network, transparent 2D PG sheets covered the holes of the SCNT networks and increased the current collection area of the electrodes. At the same time, the long SCNT act as a bridge between PG sheets and create new electrical percolation channels in PG conductive networks, enhanced the conductivity of the electrodes. Furthermore, the interfacial interaction in SCNT-SCNT and PG-PG junctions also enhanced (Figure S1). The tight connection may be the result of three different phenomena. First, conductive and stretchable PEDOT chains changed from coil conformation to linear conformation after DMSO added. Coil conformation conductive PEDOT chains are surrounded by insulating PSS in the original PEDOT:PSS solution.38 Coulombic interaction between the conductive PEDOT chains and insulating PSS chains is effectively weakened when DMSO was added. Consequently, PEDOT chains changed to linear conformation as the coulombic repulsions among the positive charges in PEDOT chains are dominant. Second, the linear conformal conjugated aromatic PEDOT chains can strongly anchored and entangled along the surface of SCNT and PG via π–π, electrostatic and hydrophobic interactions,45 linked them together without disrupting the electronic structure. Third, the conductive and stretchable PEDOT chains not only act as an organic conductive glue connected the inorganic 1D SCNT and 2D PG together, the conductive



Page 12 of 28

PEDOT chains itself also cross-linked into conductive networks after DMSO added. It is a 3D interpenetrating SCNT-PG-PEDOT conductive network.

Figure 4. (a) Photograph, SEM microimage of nacre and the schematic illustration of the nacre-inspired 3D interconnected SCNT-PG-PEDOT conductive network. (b-d) TEM microimages of SCNT/PG mixture dispersed in PSS. (e-g) TEM microimages of SCNT/PG mixture dispersed in PEDOT:PSS. Insets are the schematic illustration of SCNT-PG (d) and SCNT-PG-PEDOT (g) conductive network structure.


Page 13 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


XPS was used to probe the chemical composition of 2D PG sheets. Figure 5a shows the XPS spectra of PG, the survey scan spectra of PG sheets reveal only C1s and O1s peaks. The relative contents of C and O elements ratio as high as ~29.25. A further fitting of C1s fine scan spectra was conducted as shown in the inset of Figure 5b. There are two peaks consist of 284.5 eV (C=C/C-C) and 286.4 eV(C-O). The C1s XPS spectrum is dominated by C=C/C-C peak and the C-O peak is hardly detected. Therefore, there is no excessive oxidation or unwanted chemical functionalization in 2D PG sheets and no chemical induced defects disrupt the band structure or degrade the electronic properties of graphene.46, 47 The change of the PEDOT chains from coil conformation to linear conformation after DMSO treatment was confirmed by Raman spectroscopy. Figure 5c shows the Raman spectra of pristine and DMSO treated PEDOT:PSS. The strongest band between 1400 and 1500 cm-1 corresponding to the Cα=Cβ stretching vibration of the five-membered thiophene ring on the PEDOT chains.48 The Cα=Cβ peak redshift from1428 to 1422 cm-1 after DMSO treatment. This redshift indicates that the resonant structure of PEDOT chains changed from benzoid structure to a more conductive quinoid structure. The benzoid structure is the favorite structure for a coil conformation and the quinoid structure is the favorite structure for a linear conformation. Therefore, the redshift phenomena in Raman spectra confirmed the PEDOT chains changed from coil to linear conformational. After PEDOT chains changed to quinoid structure, the conjugated π-electrons could be delocalized over the whole PEDOT chains and thus resulting in more conductive PEDOT.49 The interfacial interactions between inorganic SCNT-PG and organic PEDOT chains was also confirmed by Raman spectroscopy. Figure 5d shows the Raman spectra of SCNT, PG, SCNT-PG-PEDOT. The G-band of SCNT and PG in Raman spectra are upshifted to 1578 cm

−1

,

indicating the p-type doping of SCNT and PG. This phenomenon confirmed the interfacial interactions between the inorganic SCNT-PG and organic PEDOT chains. In addition, the phenomena also



Page 14 of 28

demonstrated the effective charge-transfer between conjugated PEDOT chains and SCNT-PG networks.50, 51

Figure 5. (a) Full-scale XPS spectra and (b) C 1 s spectra of PG sheets. Raman spectra of (c) PEDOT:PSS before and after the DMSO post-treatment and (d）SCNT, PG, and SCNT-PG-PEDOT.

The SCNT-PG conductive network without interface-enhanced conductive glue PEDOT was easily damaged during peeled off TE from the template (Figure 6a). It mainly due to the weak interfacial interactions between the simple physical contact SCNT and PG. The laminar 2D PG exhibit a planar sheet structure and the 1D SCNT present a tubular structure. A part of PG sheets protruded from the surface of the TE as a result of the weak interfacial interactions. The loosely contact SCNT-PG conductive network could not resist external forces and inducing destructive interface sliding between ACS Paragon Plus Environment

Page 15 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


SCNT and PG under stress.52,53 The long SCNT act as a bridge at the breakage of the conductive network and bridges the separated PG sheets. Compared with the loose contact SCNT-PG network, 3D interconnected SCNT-PG-PEDOT conductive network still remained its complete conductive structure after peeled off TE from the template as shown in Figure 6b and c. The long 1D SCNT bundles and 2D PG sheets in the conductive networks were well distributed and tightly contacted. SEM image and corresponding element mapping images of the TE reveal organic conductive PEDOT chains uniformly anchored and entangled along the surface of SCNT and PG (Figure 6d). The organic PEDOT filled the holes of the porous SCNT-PG conductive networks and just like a skin wrapped around the 3D SCNT-PG skeleton induced a smooth surface.

Figure 6. SEM microimages of (a) SCNT-PG, (b, c) SCNT-PG-PEDOT conductive network after peeled off from the template. (d) SEM microimage and corresponding elements mapping images of the TE surface.

Figure 7 shows the 3D AFM image of SCNT-PG-PEDOT conductive network on SC substrates with different sheet resistance. A lower sheet resistance represents a thicker SCNT-PG-PEDOT conductive layer embedded on the substrate surface. The conductive network structure on the substrate surface is obvious. The surface roughness of TE decreased significantly after embedded the conductive SCNT-PG-PEDOT layer on the top surface of SC substrate. It mainly due to the 2D structure PG planar



Page 16 of 28

sheets can effectively cover the surface of SC substrate and reduce the surface roughness of the TE.28 Meanwhile, PEDOT macromolecules covered the folds and wrinkles of PG sheets could further reduce the surface roughness of the TE. Hence, as the thickness of the SCNT-PG-PEDOT layer increases, the influence of the SC substrate on the surface roughness of the TE gradually decreases. The TE exhibit a smooth surface topography. The Ra of the TE varies from 6.1 nm to 2.2 nm along with the resistance value changes. The planarization of the surface will contribute to a reduction in the risk of leakage current and a longer optoelectronic device lifetime.54


Page 17 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. 3D AFM images of SCNT-PG-PEDOT conductive networks on SC substrate with different sheet resistance (a)158.8 Ω/sq, (b) 105.5 Ω/sq, (c) 46 Ω/sq, (d) 36.7 Ω/sq, (e) 25.6 Ω/sq.

Figure 8a shows the optoelectronic performance of our SCNT-PG-PEDOT based TE. The SCNT-PG-PEDOT based TE exhibit a lower resistance at a relative high transmittance range compared with other solution-processed CNT-graphene based TE. In order to compare the transmittance and



Page 18 of 28

resistance values comprehensively, the optoelectronic performance of TE is quantified by a figure of merit (FoM), defined by the ratio of direct current (DC) electrical conductivity to optical conductivity (σDC/σOP).24

σDC σOP

=

188.5 Rs T 2 - 1 1

(1)

where, Rs is the sheet resistance and T is the transmittance of TE. A high FoM value means a high optical transmittance with a low sheet resistance and thus a better optoelectronic performance. The calculated FoM of SCNT-PG-PEDOT is 43.4 when the flexible TE exhibits a sheet resistance of 46 Ω/sq with a transmittance of 83.5%. The FoM value is much higher than merely SCNT and graphene hybrid TE, such as a simple mixture of SCNT and graphene film prepared by spin coating,55 SCNT and graphene oxide (GO) hybrid film prepared by Langmuir–Blodgett assembly or further thermal reduced film,56 multiwall carbon nanotube (MCNT) and graphene hybrid film prepared by rod coating..57 Although the thionyl chloride (SOCl2) doped SCNT-graphene TE exhibit a comparable FoM value (10.03) with a sheet resistance and transmittance of 240 Ω/sq and 80.2%.55 However, SOCl2 is highly corrosive and harmful to the human body, which make it unsuitable for flexible and wearable devices.58 Furthermore, the instability of chemical doping in the environment will also affect the optoelectronic performance of the device.28 On the contrary, SCNT-PG-PEDOT based TE exhibit excellent environmental stability. The sheet resistance of the TE nearly unchanged under different temperature (Figure S2). For SCNT-PG mixture dispersed by insulating PSS, the sheet resistance of SCNT-PG film is as high as thousands of ohm. It is due to the loose interfacial contact between SCNT and PG at the junctions and the insulating PSS wrapped their surface further increased the contact resistance. In addition to excellent optoelectronic performance, the SCNT-PG-PEDOT based TE possess excellent mechanical flexibility, which is essential for flexible and wearable devices. The conductive SCNT-PG-PEDOT network embedded into the substrate not only forming a percolating conducting network but also reinforced the composite structure of the substrates simultaneously. The tensile ACS Paragon Plus Environment

Page 19 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


strength and elongation of the prepared TE are around 31.6 MPa and 33.2% respectively with transmittance above 80%. Figure 8b compares the changes of sheet resistance of SCNT-PG, SCNT-PG-PEDOT and ITO based TE as a function of the bending cycles with a bending radius of 3 mm. The sheet resistance of the ITO increased rapidly under bending due to crack formation. The sheet resistance of SCNT-PG based TE increased by ~40% compared to its initial value due to interfacial sliding. In contrast, the sheet resistance of SCNT-PG-PEDOT based TE increased slightly less than 3% compared to its initial value. More interestingly, we found that the sheet resistance of SCNT-PG-PEDOT based TE nearly unchanged after peeled off from the petri dish. However, the sheet resistance of SCNT-PG based TE increased several folds compared to its initial value after peeled off from the petri dish. The conductive mechanism of nacre-inspired 3D interconnected SCNT-PG-PEDOT based TE under normal and bending deformation conditions is illustrated in Figure 8c. The organic conductive PEDOT chains like a glue linked 1D SCNT and 2D PG into a 3D interconnected conductive network. Under stretching and compressing, the folded PEDOT chains were stretched along the direction of tensile stress. The long PEDOT chains not only provide strong interfacial interactions between SCNT and PG but also supply enough movement space for SCNT and PG when external force loading and thus absorb much more energy. It effectively avoids the destructive slippage between adjacent SCNT and PG.59 When the external force is unloaded, the PEDOT chains could restore to original shapes. Therefore, the nacre-inspired 3D interconnected SCNT-PG-PEDOT conductive network not only leading an excellent optoelectronic performance but also superior mechanical flexibility. The flexible TE retained its conductivity consistently even when it was compressed and stretched (Figure 8d-f), indicating the excellent flexibility of the electrode. As shown in Figure 8g, the SC substrate based TE could conform to skin topography naturally. The flexible TE can sustain various strains no matter in stretched or twisted state. Furthermore, the edible SC substrate based TE can easily adherent to the subject surface without using adhesive and conform to its topography naturally (Figure



Page 20 of 28

S3). This feature is essential for flexible and wearable electronic devices, which not only enable the highly long-term operational reliability of device, but also make people feel comfortable just like a second skin without sensing the presence of devices.60 Therefore, the edible SC substrates are more suitable for flexible and wearable electronic devices than present widely used plastic based substrates.

Figure 8. (a) Comparison of optoelectronic performance of our SCNT-PG-PEDOT based TE with other TE. The dash line indicates the fit to equation (1), corresponding to σDC/σOP= 5, 10, 20, and 50 respectively. (b) Resistance relative change of SCNT-PG, SCNT-PG-PEDOT and commercial ITO based TE versus bending cycles in bending test. △R, the sheet resistance changes during bending test; R0, the initial sheet resistance before bending test. Insets are the schematic illustration of the bent state and a photographic image of the flexible SCNT-PG-PEDOT based TE. (c) Schematic illustrations of the nacre-inspired SCNT-PG-PEDOT based TE conductive mechanism under stretching. (d-f) Photographs of the excellent flexibility of SCNT-PG-PEDOT based TE. (g) Photographs showing a SC substrate based TE attached on the skin of the human. The attached SC substrate based TE is capable of conformal deformations along with the skin.

Figure 9 shows the time elapse images of edible SC substrate based TE dissolved by 3 wt% lysozyme in CH3COOH-CH3COONa (pH=4.5) buffer at room temperature via a green process. ACS Paragon Plus Environment

Page 21 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Lysozyme is very widely distributed in nature, such as human and other animal tissues and tissue fluids. The edible SC substrate slowly disappeared by simple dissolution. The dissolution process caused the TE to physically disintegrated and lost the mechanical strength after only 8 min. Afterwards, the SC substrate based TE can’t be picked up and gradually disappeared (dissolved). Afterward, the SCNT-PG-PEDOT was recovered by a membrane process for further fabrication of conductive and reinforcement composites. As the decomposed edible SC with a high degree to get recycled in the nature, this process would not bring any environmental pollution problems and achieving completely “green” transience. The degradation of SC film can also occur over periods of time ranging from several days, months to years by degrading through micro-organisms in soil and water in the nature.61 These results suggest that the transparent biomass-derived edible SC film provides a biodegradable alternative to conventional plastic substrates to solve the current thorny E-waste problem. Furthermore, recent studies have demonstrated that graphene formed on food such as bread, potato skins, and coconut shells could be used as flexible, biodegradable and edible electronics,62 and the food-based electronics even could be ingested and assimilated as metabolized nutrients.63,64 This leads us to believe that this high performance biodegradable TE would potentially allow applications such as edible electronics, after further research and a thorough toxicity study.

Figure 9. Dissolution behaviors of the biodegradable SC substrate based TE.

4. Conclusions



Page 22 of 28

In summary, we have demonstrated that biodegradable and wearable TE fabricated by embedding nacre-inspired 3D interconnected conductive SCNT-PG-PEDOT networks into transparent edible SC based substrate. Natural potato and crab shells derived SC films with a smooth surface morphology exhibit excellent optical properties are suitable for substrates of optoelectronic devices. Nacre-inspired interface design are introduced to construct a 3D interconnected and interpenetrating conductive networks. The results show that the organic stretchable and conductive PEDOT chains anchored on the interface of inorganic 1D SCNT bundles and 2D PG sheets, not only reduced the junction resistance but also enhanced the mechanical stability of the conductive networks. The biodegradable and flexible TE exhibited excellent optoelectronic property, mechanical flexibility, and degradability. The realization of edible transparent SC substrate based high performance TE promises a bright future for the development of flexible, wearable green electronics and edible electronics. ASSOCIATED CONTENT Supporting Information The material is available free of charge via the Internet at http://pubs.acs.org. TEM microimages of SCNT and PG sheets connected by PEDOT, absolute values of the sheet resistance relative change of the TE under different temperature, and the photograph of edible SC substrate based TE adherent to the subject surface without using adhesives. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. Tel/Fax: +86-22-83955054. Notes The authors declare no competing financial interest. ACKNOLEGMENTS


Page 23 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


This work was supported by the New Materials Research Key Program of Tianjin (No. 16ZXCLGX00090), the National Key Research and Development Program of China (No. 2016YFB0303000). REFERENCES (1) Ogunseitan, O. A.; Schoenung, J. M.; Saphores, J. D. M.; Shapiro, A. A. The Electronics Revolution: From E-Wonderland to E-Wasteland. Science 2009, 326, 670-671. (2) Zou, Z.; Zhu, C.; Li, Y.; Lei, X.; Zhang, W.; Xiao, J. Rehealable, Fully Recyclable, and Malleable Electronic Skin Enabled by Dynamic Covalent Thermoset Nanocomposite. Sci. Adv. 2018, 4, eaaq0508. (3) Lei, T.; Guan, M.; Liu, J.; Lin, H. C.; Pfattner, R.; Shaw, L.; Mcguire, A. F.; Huang, T. C.; Shao, L.; Cheng, K. T. Biocompatible and Totally Disintegrable Semiconducting Polymer for Ultrathin and Ultralightweight Transient Electronics. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 5107-5112. (4) Fu, K. K.; Wang, Z.; Dai, J.; Carter, M.; Hu, L. B. Transient Electronics: Materials and Devices. Chem. Mater. 2016, 28, 3527-3539. (5) Someya, T.; Bao, Z.; Malliaras, G. G. The Rise of Plastic Bioelectronics. Nature 2016, 540, 379-385. (6) Irimia-Vladu, M. "Green" Electronics: Biodegradable and Biocompatible Materials and Devices for Sustainable Future. Chem. Soc. Rev. 2014, 43, 588-610. (7) Gao, X.; Huang, L.; Wang, B.; Xu, D.; Zhong, J.; Hu, Z.; Zhang, L.; Zhou, J. Natural Materials Assembled, Biodegradable, and Transparent Paper-Based Electret Nanogenerator. ACS Appl. Mater. Interfaces 2016, 8, 35587-35592. (8) Ko, J.; Nguyen, L. T. H.; Surendran, A.; Tan, B. Y.; Ng, K. W.; Leong, W. L. Human Hair Keratin for Biocompatible Flexible and Transient Electronic Devices. ACS Appl. Mater. Interfaces 2017, 9, 43004-43012. (9) Lee, D.; Lim, Y.-W.; Im, H.G.; Jeong, S.; Ji, S.; Kim, Y. H.; Choi, G.-M.; Park, J.U.; Lee, J.Y.; Jin, J.; Bae, B.S. Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics. ACS Appl. Mater. Interfaces 2017, 9, 24161-24168. (10) Song, Y.; Kim, S.; Heller, M. J. An Implantable Transparent Conductive Film with Water Resistance and Ultrabendability for Electronic Devices. ACS Appl. Mater. Interfaces 2017, 9, 42302-42312. (11) Omenetto, F. G.; Kaplan, D. L. A New Route for Silk. Nat. Photonics 2008, 2, 641-643.



Page 24 of 28

(12) Kim, D.H.; Viventi, J.; Amsden, J. J.; Xiao, J.; Vigeland, L.; Kim, Y.S.; Blanco, J. A.; Panilaitis, B.; Frechette, E. S.; Contreras, D.; Kaplan, D. L.; Omenetto, F. G.; Huang, Y.; Hwang, K.C.; Zakin, M. R.; Litt, B.; Rogers, J. A. Dissolvable Films of Silk Fibroin for Ultrathin Conformal Bio-Integrated Electronics. Nat. Mater. 2010, 9, 511-517. (13) Zhu, H.; Luo, W.; Ciesielski, P. N.; Fang, Z.; Zhu, J. Y.; Henriksson, G.; Himmel, M. E.; Hu, L. Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications. Chem. Rev. 2016, 116, 9305-74. (14) Hu, L.; Zheng, G.; Yao, J.; Liu, N.; Weil, B.; Eskilsson, M.; Karabulut, E.; Ruan, Z.; Fan, S.; Bloking, J. T.; McGehee, M. D.; Wågberg, L.; Cui, Y. Transparent and Conductive Paper from Nanocellulose Fibers. Energ. Environ. Sci. 2013, 6, 513-518. (15) Liu, Y.; Qi, N.; Song, T.; Jia, M.; Xia, Z.; Yuan, Z.; Yuan, W.; Zhang, K. Q.; Sun, B. Highly Flexible and Lightweight Organic Solar Cells on Biocompatible Silk Fibroin. ACS Appl. Mater. Interfaces 2014, 6, 20670-20675. (16) Jeong, H.; Baek, S.; Han, S.; Jang, H.; Kim, S. H.; Lee, H. S. Novel Eco-Friendly Starch Paper for Use in Flexible, Transparent, and Disposable Organic Electronics. Adv. Funct. Mater. 2018, 28, 1704433-n/a. (17) Bae, S.; Kim, H.; Lee, Y.; Xu, X.; Park, J. S.; Zheng, Y.; Balakrishnan, J.; Lei, T.; Kim, H. R.; Song, Y. I.; Kim, Y. J.; Kim, K. S.; Ozyilmaz, B.; Ahn, J. H.; Hong, B. H.; Iijima, S. Roll-to-Roll Production of 30-Inch Graphene Films for Transparent Electrodes. Nat. Nanotech. 2010, 5, 574-578. (18) Miyamoto, A.; Lee, S.; Cooray, N. F.; Lee, S.; Mori, M.; Matsuhisa, N.; Jin, H.; Yoda, L.; Yokota, T.; Itoh, A.; Sekino, M.; Kawasaki, H.; Ebihara, T.; Amagai, M.; Someya, T. Inflammation-Free, Gas-Permeable, Lightweight, Stretchable on-Skin Electronics with Nanomeshes. Nat. Nanotech. 2017, 12, 907–913. (19) Cai, J.; Lv, C.; Watanabe, A. Laser Direct Writing and Selective Metallization of Metallic Circuits for Integrated Wireless Devices. ACS Appl. Mater. Interfaces 2018, 10, 915-924. (20) Jung, S.; Kim, J. H.; Kim, J.; Choi, S.; Lee, J.; Park, I.; Hyeon, T.; Kim, D.-H. Reverse-Micelle-Induced Porous Pressure-Sensitive Rubber for Wearable Human–Machine Interfaces. Adv. Mater. 2014, 26, 4825-4830. (21) You, Y.-M.; Liao, W. Q.; Zhao, D.; Ye, H.-Y.; Zhang, Y.; Zhou, Q.; Niu, X.; Wang, J.; Li, P.-F.; Fu, D. W.; Wang, Z.; Gao, S.; Yang, K.; Liu, J. M.; Li, J.; Yan, Y.; Xiong, R. G. An Organic-Inorganic Perovskite Ferroelectric with Large Piezoelectric Response. Science 2017, 357, 306-309. (22) Tang, Z.; Jia, S.; Wang, F.; Bian, C.; Chen, Y.; Wang, Y.; Li, B. Highly Stretchable Core–Sheath Fibers via Wet-Spinning for Wearable Strain Sensors. ACS Appl. Mater. Interfaces 2018, 10, 6624-6635.


Page 25 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(23) Sohn, H.; Kim, S.; Shin, W.; Lee, J. M.; Lee, H.; Yun, D.-J.; Moon, K.-S.; Han, I. T.; Kwak, C.; Hwang, S. J. Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet–Ag Nanowire Hybrid. ACS Appl. Mater. Interfaces 2018, 10, 2688-2700. (24) Miao, J. L.; Liu, H.H.; Li, W.; Zhang, X. X. Mussel-Inspired Polydopamine-Functionalized Graphene as a Conductive Adhesion Promoter and Protective Layer for Silver Nanowire Transparent Electrodes. Langmuir 2016, 32, 5365-5372. (25) Miao, J. L.; Liu, H. H.; Li, C.B.; Zhang, X.X. Graphene-Based Film Reduced by a Chemical and Thermal Synergy Method as a Transparent Conductive Electrode. Sci. Adv. Mater. 2016, 8, 1066-1073. (26) Kim, S. H.; Song, W.; Jung, M. W.; Kang, M.-A.; Kim, K.; Chang, S.-J.; Lee, S. S.; Lim, J.; Hwang, J.; Myung, S.; An, K.S. Carbon Nanotube and Graphene Hybrid Thin Film for Transparent Electrodes and Field Effect Transistors. Adv. Mater. 2014, 26, 4247-4252. (27) King, P. J.; Khan, U.; Lotya, M.; De, S.; Coleman, J. N. Improvement of Transparent Conducting Nanotube Films by Addition of Small Quantities of Graphene. ACS Nano 2010, 4, 4238-4246. (28) Du, J.; Pei, S.; Ma, L.; Cheng, H. M. 25th Anniversary Article: Carbon Nanotube- and Graphene-Based Transparent Conductive Films for Optoelectronic Devices. Adv. Mater. 2014, 26, 1958-1991. (29) Shi, J.; Li, X.; Cheng, H.; Liu, Z.; Zhao, L.; Yang, T.; Dai, Z.; Cheng, Z.; Shi, E.; Yang, L.; Zhang, Z.; Cao, A.; Zhu, H.; Fang, Y. Graphene Reinforced Carbon Nanotube Networks for Wearable Strain Sensors. Adv. Funct. Mater. 2016, 26, 2078-2084. (30) Zhu, Y.; Li, L.; Zhang, C.; Casillas, G.; Sun, Z.; Yan, Z.; Ruan, G.; Peng, Z.; Raji, A. R. O.; Kittrell, C.; Hauge, R. H.; Tour, J. M. A Seamless Three-Dimensional Carbon Nanotube Graphene Hybrid Material. Nat. Comm. 2012, 3, 1225. (31) Zavareze, E. R.; Pinto, V. Z.; Klein, B.; El Halal, S. L.; Elias, M. C.; Prentice-Hernã, n. C.; Dias, A. R. Development of Oxidised and Heat-Moisture Treated Potato Starch Film. Food Chem. 2012, 132, 344-350. (32) Chang, P. R.; Jian, R.; Yu, J.; Ma, X. Starch-Based Composites Reinforced with Novel Chitin Nanoparticles. Carbohyd. Polym. 2010, 80, 420-425. (33) Hong, M.S.; Choi, G.M.; Kim, J.; Jang, J.; Choi, B.; Kim, J. K.; Jeong, S.; Leem, S.; Kwon, H. Y.; Hwang, H.B.; Im, H.G.; Park, J.U.; Bae, B.S.; Jin, J. Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics. Adv. Funct. Mater. 2017, 1705480-n/a. 10.1002/adfm.201705480.



Page 26 of 28

(34) Wang, R.; Gao, S.; Yang, Z.; Li, Y.; Chen, W.; Wu, B.; Wu, W. Engineered and Laser-Processed Chitosan Biopolymers for Sustainable and Biodegradable Triboelectric Power Generation. Adv. Mater. 2018, 30, 1706267-n/a. (35) Yan, N.; Chen, X. Don't Waste Seafood Waste. Nature 2015, 524, 155-157. (36) Xu, Y. X.; Kim, K. M.; Hanna, M. A.; Nag, D. Chitosan-Starch Composite Film: Preparation and Characterization. Ind. Crop. Prod. 2005, 21, 185-192. (37) Cheng, Q.; Duan, J.; Zhang, Q.; Jiang, L. Learning from Nature: Constructing Integrated Graphene-Based Artificial Nacre. ACS Nano 2015, 9, 2231-2234. (38) Wang, Y.; Zhu, C.; Pfattner, R.; Yan, H.; Jin, L.; Chen, S.; Molinalopez, F.; Lissel, F.; Liu, J.; Rabiah, N. I. A Highly Stretchable, Transparent, and Conductive Polymer. Sci. Adv. 2017, 3, e1602076. (39) Sun, H. S.; Chiu, Y. C.; Chen, W. C. Renewable Polymeric Materials for Electronic Applications. Polym. J. 2017, 49, 61-73. (40) Mathew, S.; Abraham, T. E. Characterisation of Ferulic Acid Incorporated Starch-Chitosan Blend Films. Food Hydrocolloid 2008, 22, 826-835. (41) Song, J.; Chen, C.; Wang, C.; Kuang, Y.; Li, Y.; Jiang, F.; Li, Y.; Hitz, E.; Zhang, Y.; Liu, B.; Gong, A.; Bian, H.; Zhu, J. Y.; Zhang, J.; Li, J.; Hu, L. B. Superflexible Wood. ACS Appl. Mater. Interfaces 2017, 9, 23520-23527. (42) Jin, Y.; Wang, K.; Cheng, Y.; Pei, Q.; Xu, Y.; Xiao, F. Removable Large-Area Ultrasmooth Silver Nanowire Transparent Composite Electrode. ACS Appl. Mater. Interfaces 2017, 9, 4733-4741. (43) Zhu, H.; Xiao, Z.; Liu, D.; Li, Y.; Weadock, N. J.; Fang, Z.; Huang, J.; Hu, L. B. Biodegradable Transparent Substrates for Flexible Organic-Light-Emitting Diodes. Energ. Environ. Sci. 2013, 6, 2105. (44) Paton, K. R.; Varrla, E.; Backes, C.; Smith, R. J.; Khan, U.; O'Neill, A.; Boland, C.; Lotya, M.; Istrate, O. M.; King, P.; Higgins, T.; Barwich, S.; May, P.; Puczkarski, P.; Ahmed, I.; Moebius, M.; Pettersson, H.; Long, E.; Coelho, J.; O'Brien, S. E.; McGuire, E. K.; Sanchez, B. M.; Duesberg, G. S.; McEvoy, N.; Pennycook, T. J.; Downing, C.; Crossley, A.; Nicolosi, V.; Coleman, J. N. Scalable Production of Large Quantities of Defect-Free Few-Layer Graphene by Shear Exfoliation in Liquids. Nat. Mater. 2014, 13, 624-630. (45) Fan, M.; Zhu, C.; Liu, L.; Wu, Q.; Hao, Q.; Yang J.; Sun, D. Modified PEDOT by Benign Preparing N-Doped Reduced Graphene Oxide as Potential Bio-Electrode Coating Material. Green Chem. 2016, 18, 1731-1737. (46) Ciesielski, A.; Samori, P. Graphene via sonication assisted liquid-phase exfoliation. Chem Soc Rev. 2014, 43, 381-398.


Page 27 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(47) Yang, Y.; Zhao, R.; Zhang, T.; Zhao, K.; Xiao, P.; Ma, Y.; Ajayan, P. M.; Shi, G. Q.; Chen, Y. S. Graphene-Based Standalone Solar Energy Converter for Water Desalination and Purification. ACS Nano 2018, 12, 829-835. (48) McGillivray, D.; Thomas, J. P.; Abd-Ellah, M.; Heinig, N. F.; Leung, K. T. Performance Enhancement by Secondary Doping in PEDOT:PSS/Planar-Si Hybrid Solar Cells. ACS Appl. Mater. Interfaces 2016, 8, 34303-34308. (49) Chou, T.R.; Chen, S.H.; Chiang, Y.T.; Lin, Y.T.; Chao, C.Y. Highly Conductive PEDOT:PSS Films by Post-Treatment with Dimethyl Sulfoxide for ITO-Free Liquid Crystal Display. J. Mater. Chem. C 2015, 3, 3760-3766. (50) Park, H. S.; Choi, B. G.; Hong, W. H.; Jang, S. Y. Interfacial Interactions of Single-walled Carbon Nanotube/Conjugated Block Copolymer Hybrids for Flexible Transparent Conductive Films. J. Phys. Chem. C 2012, 116, 7962-7967. (51) Liu, Z.; Parvez, K.; Li, R.; Dong, R.; Feng, X. L.; Mullen, K. Transparent Conductive Electrodes from Graphene/PEDOT:PSS Hybrid Inks for Ultrathin Organic Photodetectors. Adv. Mater. 2015, 27, 669-675. (52) Yang, Y.; Kim, N. D.; Varshney, V.; Sihn, S.; Li, Y.; Roy, A. K.; Tour, J. M.; Lou, J. In Situ Mechanical Investigation of Carbon Nanotube-Graphene Junction in Three-Dimensional Carbon nanostructures. Nanoscale 2017, 9, 2916-29242. (53) Ma, T.; Gao, H.-L.; Cong, H. P.; Yao, H. B.; Wu, L.; Yu, Z. Y.; Chen, S. M.; Yu, S. H. A Bioinspired Interface Design for Improving the Strength and Electrical Conductivity of Graphene-Based Fibers. Adv. Mater. 2018, DOI: 10.1002/adma.201706435. (54) Gaynor, W.; Burkhard, G. F.; McGehee, M. D.; Peumans, P. Smooth Nanowire/Polymer Composite Transparent Electrodes. Adv. Mater. 2011, 23, 2905-2910. (55) Tung, V. C.; Chen, L. M.; Allen, M. J.; Wassei, J. K.; Nelson, K.; Kaner, R. B.; Yang, Y. Low-Temperature Solution Processing of Graphene−Carbon Nanotube Hybrid Materials for High-Performance Transparent Conductors. Nano Lett. 2009, 9, 1949-1955. (56) Zheng, Q.; Zhang, B.; Lin, X.; Shen, X.; Yousefi, N.; Huang, Z. D.; Li, Z.; Kim, J.K. Highly Transparent and Conducting

Ultralarge

Graphene

Oxide/Single-Walled

Carbon

Nanotube

Hybrid

Films

Produced

by

Langmuir-Blodgett Assembly. J. Mater. Chem. 2012, 22, 25072-25082. (57) He, L.; Tjong, S. C. Aqueous Graphene Oxide-Dispersed Carbon Nanotubes as Inks for the Scalable Production of All-Carbon Transparent Conductive Films. J. Mater. Chem. C 2016, 4, 7043-7051.



Page 28 of 28

(58) Cataldi, P.; Ceseracciu, L.; Athanassiou, A.; Bayer, I. S. Healable Cotton–Graphene Nanocomposite Conductor for Wearable Electronics. ACS Appl. Mater. Interfaces 2017, 9, 13825-13830. (59) Valentini, L. Bio-Inspired Materials and Graphene for Electronic Applications. Mater. Lett. 2015, 148, 204-207. (60) Huang, X.; Liu, Y.; Cheng, H.; Shin, W.-J.; Fan, J. A.; Liu, Z.; Lu, C. J.; Kong, G. W.; Chen, K.; Patnaik, D.; Lee, S. H.; Hage-Ali, S.; Huang, Y.; Rogers, J. A. Materials and Designs for Wireless Epidermal Sensors of Hydration and Strain. Adv. Funct. Mater. 2014, 24, 3846-3854. (61) Bonacchini, G. E.; Bossio, C.; Greco, F.; Mattoli, V.; Kim, Y.-H.; Lanzani, G.; Caironi, M. Tattoo-Paper Transfer as a Versatile Platform for All-Printed Organic Edible Electronics. Adv. Mater. 2018, DOI: 10.1002/adma.201706091. (62) Chyan, Y.; Ye, R.; Li, Y.; Singh, S. P.; Arnusch, C. J.; Tour, J. M. Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food. ACS Nano 2018, DOI: 10.1021/acsnano.7b08539. (63) Xu, W.; Yang, H.; Zeng, W.; Houghton, T.; Wang, X.; Murthy, R.; Kim, H.; Lin, Y.; Mignolet, M.; Duan, H.; Yu, H.; Slepian, M.; Jiang, H. Food-Based Edible and Nutritive Electronics. Adv. Mater. Technol. 2017, 2, 1700181-n/a. (64) Berglund, J. Technology You Can Swallow: Moving Beyond Wearable Sensors, Researchers Are Creating Ingestible Ones. IEEE Pulse 2018, 9, 15-18.

TOC graphic


Biodegradable Transparent Substrate Based on Edible Starch

Recommend Documents